Sonographic measurement of calcaneal volume for determination of skeletal age in children.

Purpose: The purposes of this study were first to prospectively evaluate the feasibility of using sonographic measurements of volume of the ossified part of the calcaneus to determine skeletal age in healthy children and second, to provide normal ranges of this volume by sex and age up to 6 years.

Methods: Four hundred normal girls and boys ranging in age from 1 day to 6 years were examined sonographically to determine the volume of the calcaneal ossification center. The children were randomly divided into 2 groups. The first group (300 children) was used to determine normal values for the mean calcaneal volume by age and sex. The second group (100 children) was used to validate those normal values.

Results: The sonographically determined volume of the calcaneal ossification center correlated well with the chronologic age of the children. The calcaneal ossification centers of boys were larger than those of girls within the same age groups from ages 2 to 10 months, but from 11 months to 6 years old, they were larger in the girls. The differences, however, were not statistically significant. The volume of the calcaneal ossification center increased the most between the first and second years of life, reaching 183% and 140% in girls and boys, respectively. Using the normal values obtained from the first group, we correctly predicted the chronologic age in 91% of children in the validation group. Among the remaining 9%, the error in prediction of chronologic age never exceeded 1 age interval.

Conclusions: The use of sonography provides a quantitative means of measuring calcaneal volume, and its use is feasible for determining skeletal age in children. The normal values we obtained may be used as a baseline for sonographic assessment of skeletal maturation and diagnosis of growth retardation.